Incandescent lamp having stainless steel tie wires



Jan. 30, 1968 N. J. I-QAINVONE E'II'AL 3,366,826

' TIE WIRES INCANDESCENT LAMP HAVING STAINLESS STEEL Fil ed March 2,1966 INVENTORS Nicholas J. Roinone WITNESSES and Leo 0. Werner UnitedStates Patent 3,366,826 INCANDESCENT LAMP HAVING STAINLESS STEEL TIEWIRES Nicholas J. Rainone, Clifton, and Leo C. Werner, Cedar Grove,N.J., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., acorporation of Pennsylvania Filed- Mar. 2, 1966, Ser. No. 531,129 6Claims. (Cl. 313269) This invention relates to electric lamps and hasparticular reference to an improved support structure for the lead'inwires and filament of an incandescent lamp.

Due to the length of the inner sections of the lead-in wires utilized incertain types of incandescent electric lamps, such as the so-called CC6-and CC-8 type general lighting lamps in the 50 watt and higher ratings,it is necessary to strengthen or rigi-dify the lead-in wires to preventthe mount structure from being damaged or bent out of shape should thelamp be subjected to mechanical impacts during shipment or use.Heretofore, this has been accomplished by anchoring each of the lead-inwires to the arbor of the lamp stem with a so-called tie wire ofmolybdenum, one end of which is embedded in the glass arbor and theother end whereof is wrapped or looped around the lead-in conductor.While lamps utilizing such molybdenum tie wires are entirelysatisfactory from a performance standpoint, molybdenum is ratherexpensive and, because of its hardness and stiffness, rapidly abradesthe curling dies used to loop the ends of the tie wire around the leadsrequiring the frequent replacement of such dies on the mountingmachines.

In view of the foregoing, it is the general object of the presentinvention to provide a lead wire-filament support structure for electriclamps or the like which is more economical and easier to fabricate thanthose used heretofore.

Another and more specific object is the provision of a mount assemblyfor an incandescent lamp having tie wires that reduce the overall costof the lamp without detracting from either its performance quality orability to withstand mechanical shock.

The foregoing objects, and other advantages which will become apparentas the description proceeds, are achieved in accordance with the presentinvention by fabricating the tie wires from a particular grade or typeof stainless steel instead of molybdenum.

Specifically, it has been found that a stainless steel containing fromabout 14% to 18% by weight of chromium, about 0.05 to 0.12% by weight ofcarbon, and the balance iron (marketed by the Wilber B. Driver Co.,Newark, N.J., under the trade name #430 Stainless) exhibits goodshock-resistant properties, is devoid of any impurities that wouldcontaminate the lamp, and also forms a strong bond with and is thuscapable of being firmly embedded in the glass arbor of the stem. Sincethe tie wires are not in direct contact with the filament, they are ableto withstand the temperatures which prevail within the lamp in theregion of the arbor button where they are located.

A better understanding of the invention Will be obtained by referring tothe accompanying drawing, where- FIGURE 1 is an elevational view of a 60watt CC-6 general lighting type incandescent lamp embodying theinvention, a portion of the lamp envelope being broken away to show thelamp mount; and

FIG. 2 is an enlarged elevational view of the upper portion of the lampmount.

While the present invention can be used with advantage in any type ofelectrical device having an incandescible element that is supported bylead-in conductors which Patented Jan. 30, 1968 require auxiliarystrengthening supports or tie wires, it is especially adapted for use inconjunction with electric incandescent lamps and has accordingly been soillustrated and will be so described.

In FIG. 1 there is shown a 60 watt general lighting lamp 10 having theusual glass envelope 12 that is sealed and contains a filamentmountassembly 14. Included in this mount assembly are the customarylead-in conductors or wires 15 and 16, a filament 18 of coiledrefractory wire (such as tungsten or the like) that is attached to theinner ends of the lead-in wires and bridges the space therebetween, anda vitreous or glass stem 20 through which the lead-in wires are sealed.The inner end of the stem 20 is formed into a press 21 which ishermetically sealed to the lead-in wires, and a glass arbor 22 extendsupwardly from the stem press between the wires 15 and 16 to a pointlocated a predetermined distance from the filament 18.

As is shown more particularly in FIG. 2, the end of the glass arbor 22is flattened and formed into a button 23 in which the ends of thestainless steel tie wires 24 and 25 of the present invention areembedded. The tie wires extend laterally from the button and have theiropposite ends looped around the respective lead-in Wires 15 and 16. Thestainless steel tie wires are thus fastened to the lead-in conductors atpoints located between the filament 18 and the stem press 21. While thelead-in wires are generally fabricated from nickel-plated copper and arethus relatively stiff, their length is such that they can very easily bebent or deformed should the lamp receive a mechanical impact. The tiewires eliminate this danger by coupling the leads to the arbor 22 andthus rigidifying the entire mount assembly.

As is also shown in FIG. 2, an axially-extending molybdenumfilament-support wire 26 may also be embedded in the button 22 and haveits opposite end looped around the midpoint of the coiled-coil filament18 in accordance with standard lamp-making practice.

It has been discovered that the tie wires must be fabricated from aparticular type of stainless steelotherwise the lamp may becomecontaminated with impurities, the tie wire may not retain its rigidityunder the relatively high operating temperatures which prevail withinthe lamp in the vicinity of the filament, or the tie wire may not form astrong bond with the glass button and will subsequently work free fromthe button with resultant weakening of the mount and possible lampfailure under shock conditions. A stainless steel which meets all of theforegoing critical requirements and has given excellent results, has thefollowing composition: 14.00 to 18.00% by weight of chromium, from about0.05 to 0.12% (max.) carbon and the balance iron (available as #430Stainless from Wilber B. Driver Co., Newark, NJ).

Comparative performance tests and cost analyses have shown that lampsfabricated with stainless steel tie wires having the aforesaidcomposition are equivalent, from a quality standpoint, to lamps havingmolybdenum tie wires-but that the material cost of the tie wires, perse, is reduced by approximately As will be appreciated from theforegoing, the objects of the invention have been achieved insofar asthe use of stainless steel tie wires provides a rugged high-qualitymount assembly which is inherently easier to manufacture on a massproduction basis and less expensive than the prior art mounts havingmolybdenum tie wires. Since stainless steel is not as stiff and abrasiveas molybdenum, the invention affords the additional advantage ofincreasing the life of the curling dies used on the filamentmountingmachines and, thus, reduces the maintenance cost of such machines.

While one embodiment has been shown in accordance with the patentstatutes, it will be understood that various modifications in both theconfiguration and composition of the tie Wires can be made withoutdeparting from the spirit and scope of the invention.

We claim as our invention:

1. In an electric lamp or the like having an incandescible element thatis mounted on a pair of spaced conductors of such length that they aredeformable when the lamp is mechanically impacted, the improvementcomprising a rigid elongated strengthening member that is fastened toone of said conductors, is anchored to an interiorelectrically-insulated part of the iamp structure, and i composed of astainless steel that (1) is devoid of impurities which would contaminatethe lamp, and (2) retains its rigidity at the temperatures which prevailwithin the lamp when the latter is energized.

Z. The improvement set forth in claim 1 wherein;

a part of said stainless steel strengthening member is embedded andanchored in a body of vitreous material that is located adjacent saidconductors and constitutes an integral part of the mount structuresealed within the lamp,

said conductors comprise a pair of lead-in wires, and

said stainless steel is of a type that forms a strong bond with saidbody of vitreous material.

3. The improvement set forth in claim 1 wherein said stainless steelstrengthening member contains from about 14% to 18% by weight ofchromium, up to 0.12% by weight of carbon, and iron which comprises theremainder of the alloy.

4. A mount assembly for an electric incandescent lamp or the likecomprising, in combination,

a vitreous stem,

a pair of deformable lead-in wires sealed through a part of said stemand extending therebeyond in spaced apart relationship,

an incondescible member fastened to and bridging the the spaced terminalportions of said lead-in wires, and

a pair of rigid stainless sttel tie wires anchored in said stem andfastened to the respective lead-in wires at points located between saidincandescible element and the part of said stem through which saidlead-in wires are sealed,

one end of each of said tie wires being looped around the associatedlead-in Wire and the opposite ends of said tie wires being embedded in apart of said stem that is remote from the part thereof through which thelead-in wires are sealed,

said stainless steel being of a type which (1) is devoid of impuritieswhich would contaminate the lamp, (2) retains its rigidity at thetemperatures which prevail within the lamp when the latter is energized,and (3) forms a strong bond with the part of said stem in which it ispartially embedded.

5. The mount assembly set forth in claim 4 wherein;

said incandescible element comprise a filament of refractory metal wire,

said stem is terminated by a press and an arbor that extendslongitudinally from said press and between said lead-in wires,

said tie wires are embedded in said arbor, and

said lead-in wires are sealed through said stem press.

6. The mount assembly set forth in claim 4 wherein said stainless steeltie wires have the following composition:

Percent by weight (Ihromium 14.00 to 18.00 Carbon 0.05 to 0.12 IronBalance References Cited UNITED STATES PATENTS 1,374,766 4/1921 Ozaki313-271 1,615,654 1/1927 Ryder 313-278 2,425,865 8/1947 Cartun 313-2793,007,074 10/1961 Swasey et al7 313-277 X FOREIGN PATENTS 714,761 9/1954Great Britain.

JOHN W. HUCKERT, Primary Examiner.

R. F, POLISSACK, Assistant Examiner.

1. IN AN ELECTRIC LAMP OR THE LIKE HAVING AN INCANDESCIBLE ELEMENT THATIS MOUNTED ON A PAIR OF SPACED CONDUCTORS OF SUCH LENGTH THAT THEY AREDEFORMABLE WHEN THE LAMP IS MECHANICALLY IMPACTED, THE IMPROVEMENTCOMPRISING A RIGID ELONGATED STRENGTHENING MEMBER THAT IS FASTENED TOONE OF SAID CONDUCTORS, IS ANCHORED TO AN INTERIORELECTRICALLY-INSULATED PART OF THE LAMP STRUCTURE, AND IS COMPOSED OF ASTAINLESS STEEL THAT (1) IS DEVOID OF IMPURITIES WHICH WOULD CONTAMINATETHE LAMP, AND (2) RETAINS ITS RIGIDITY AT THE TEMPERATURES WHICH PREVAILWITHIN THE LAMP WHEN THE LATTER IS ENERGIZED.